Drive trains of motor vehicles having a drive assembly, and an automatic transmission with frictionally engaging shift elements being positioned between the drive assembly and an output, in which power is lost during the execution of shifts under load, are commonly known in the state of the art. In this case, the DE 198 50 549 A1 teaches a drive train of a hybrid vehicle having a drive assembly that comprises a combustion engine and an electric machine, wherein an automatic transmission is positioned between the drive assembly and an output, and is designed as a double clutch transmission, and wherein the clutches of a double clutch of a double clutch transmission serve as friction shift elements during the execution of shifts under load.
In a construction of load shift devices, especially in the construction of the traction upshifts or traction downshifts, such a drive train, with the use of frictional shift elements of the automatic transmission, creates a loss of power at the frictional contacts. Such a power loss which has to be absorbed by the frictional shift elements which results in on one hand an increased wear of the shift elements, on the other hand, unnecessary gasoline consumption. Thus, there is a need for methods of operating a drive train having an automatic transmission that comprises frictional load shift elements through which power loss can be lowered at the frictional shift elements to reduce on one hand the wear of the frictional shift elements and on the other hand to reduce the consumption of gasoline.